Internal-combustion engines – Starting device – Auxiliary fuel supply device
Patent
1996-12-20
1998-07-07
Solis, Erick R.
Internal-combustion engines
Starting device
Auxiliary fuel supply device
123525, 123576, F02N 1700
Patent
active
057752826
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to fuel injection systems for internal combustion engines.
BACKGROUND ART
Fuel injection systems for internal combustion engines can be adapted to supply liquid fuels to the inlet manifold for each cylinder of the engine. This system is known as multi-point liquid fuel injection. By suitable control of the operation of the injectors accurate amounts of liquid fuel can be supplied directly to each cylinder depending upon engine conditions and demand characteristics for vaporisation and combustion in the cylinder.
There is a problem in that for liquid fuel injection to be accurate the fuel in the injectors adjacent the injection point must be liquid at all times. The environment around each cylinder, however, can at times during engine operation be very hot and such a temperature in this region is not conducive to injection of a liquid fuel which has a low boiling point.
One particular time in which serious problems can occur is when an engine has been turned off for some time after running and the fuel rails, body of the inlet manifold and the injector or injectors have heated considerably to the stage that the liquid fuel in the injectors and even in the fuel rails has vaporised so that the rails are full of gaseous fuel rather than liquid fuel. This condition may be known as heat soak conditions. When it is desired to restart such an engine, the injectors which are designed to supply pressurised liquid will not supply sufficient fuel in the form of a gas and such an engine cannot easily be started. Operation of a fuel pump to circulate fresh fuel through the fuel rails and injectors is necessary for some considerable time, perhaps 15 or 30 seconds, before sufficient fresh fuel has been pumped into the fuel rail and injectors to cool them and to supply liquid fuel to the injectors to enable starting of the engine.
Another problem can exist where an engine is operated on a dual fuel system. That is, the engine has perhaps both a LPG and a petrol supply and is desired to change from one fuel to the other. Where the change is from petrol to LPG the much higher pressure LPG easily replaces the petrol but when the change is from LPG at a higher pressure to petrol at a lower pressure there is a considerable time, perhaps in the order of two minutes, where the pressure is still too high to admit petrol but the LPG pressure is not maintained because of lack of flow of LPG and hence is not high enough to prevent vaporisation of the fuel and again gas rather than liquid is supplied through the injectors.
It is the object of this invention to provide an arrangement by which an engine can be started in what may be termed heat soak conditions and also to provide arrangements where power can be maintained during changeover from one fuel to another in a dual fuel system.
DISCLOSURE OF THE INVENTION
In one form therefore the invention is said to reside in an auxiliary injector arrangement in a dual fuel supply system for an internal combustion engine, the dual fuel supply system comprising a main fuel supply system to supply at least one of the fuels using a main liquid fuel injector or injectors into at least an inlet manifold adjacent each engine cylinder of the engine, and an auxiliary fuel supply system, wherein the inlet manifold includes a throttle body and the inlet manifold is divided downstream of the throttle body to supply air to each of the cylinders of the internal combustion engine, the auxiliary fuel supply system including at least one injector for one of the fuels mounted in or adjacent the throttle body upstream or downstream of a throttle valve in the throttle body and adapted to supply fuel at times when the main injector or injectors cannot supply sufficient fuel.
Hence it will be seen by this invention that there is provided an auxiliary fuel injector located in the main inlet air stream at a point some distance from the engine block, where temperatures are not so harsh, as an alternative fuel supply system.
Because of its positioning adjacent the throttl
REFERENCES:
patent: 5203305 (1993-04-01), Porter et al.
patent: 5549083 (1996-08-01), Feuling
Derwent Abstract Accession No. 86-263582/40, Class Q53, SU1211435A, 15 Feb. 1986.
Solis Erick R.
The Energy Research and Development Corporation
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